ARJ is a tool for creating compressed file archives. It was conceived by Robert K. Jung[?] (aR.J.). It is no longer in wide use (still supported though) on many platforms. Its main use was in the BBS era, since it allowed one, even before PKZIP, to create multi-volume archives. ARJ's compression is similar to that of PKZIP 1.02.
wikipedia.org dumped 2003-03-17 with terodump